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(1) External Query: Use queries from a client (external to the TQLEngineA-Stack). These queries are sent to the TQLEngine A-Stack query end points as the payload of a message. The query return will be send back to the client as a message. These queries can not only provide client the model instance data, but also execute business logic after the TQL Project has been deployed. For example, from find and update queries, the client would be able to view and control the states of things.
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(2) Internal Query: Use queries within the models that are deployed to TQLEngine A-Stack itself. These queries execute business logic between the TQL Models themselves, independent of the client. They are included in ThingFacets and AppFacets as part of the Action/Task/Invoke 
. For example, one model may try to update another model and that can be done by executing query as part of the action.
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